Hydraulic transmission for machine tools



c. R. ALDEN HYDRAULIC T RANSMISSION FOR MACHINE TOOLS Original Filed March 17, 1932 10 Sheets-Sheet 1,

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HYDRAULIC TRANSMISSION MACHINE TOOLS Original Filed March 17, 1932 10 Sheets-Sheet s o i Inez/Mar Cairo ,PoWde/z May 21, 1946. c. R. ALDEN HYDRAULIC TRANSMISSION FOR MACHINE TOOLS 10 Sheets Sheet 7 Original Filed March 17 1952 Imzzmor Carro 50/9/02)? 3 a? fiomggs I Inward-0r camp/gave dqfiomgqs c. ALDEN HYDRAULIC TRANSMISSION FOR MACHINE TOOLS Original Filed March 17, 1952 May 21, 1946.

May 21, 1946. c. R. ALDEN 2,400,729

' I HYDRAULIC TRANSMISSION FOR MACHINE TOOLS Original Filed March 17', 1932 10 Sheets-Sheet 9 wmJj Invanfor I Cane/h? (W/den a; wad 69W x 604 I 'flfi'orne gs May 21, 1946. c. R; ALDEN HYDRAULIC TRANSMISSION FOR MACHINE TOOLS V 10 Sheets-Sheet l0 Original Filed March 17 1952 Patented May 21, 1946 SSION son MACHINE OOLS Carroll R. Alden, lJetroit, Mich., assignor to Ex-Cell-O Corporation, a corporation of Michi- Original application March 17, 1932, Serial No. 7

599,427, now Patent No. 2,000,553, dated May 7, 1935. -Divided and this application September 22, 1933, Serial No. 690,525

32 Claims.

- The present invention relates to improvements in machine tools, and has particular reference to a novel hydraulic transmission for driving some translatory power element, such for example as a reciprocatory carriage, of a machine tool. The present application is a division of my copending application Serial No. 599,427, filed March 17, 1932 (Patent No. 2,000,553).

One of the objects of the present invention resides in the provision of a. novel hydraulic transmission for driving a reversible translatory machine tool element, in which the speed of travel of the element in both directions of traverse is controlled by the rate of discharge from the exhaust end of the hydraulic motor, and more Figure 2 is a fragmentary longitudinal sectional view of the machine tool through the hydraulic motor takenalong line 22 of Fig. 3.

Fig. 3 is a fragmentary transverse sectional view of the machine tool with-the spindle sup.-

ports removed taken along line 3-3 of Fig. 1.

specifically by connecting the exhaust end of the selectively in the discharge passage to vary the rate of feed.

' Another object resides in the provision in a. new

and improved hydraulic transmission for driving the translatory element, of a direction valve, an hydraulic pilot reset mechanism operable by dogs onthe element to control the position and operaalong line 8-8 of Fig. 1, of the manual control valve.

tion of the direction valve,'and an hydraulic con- V trol valve adapted upon movement into inopera tive position to render the pilot reset mechanism V inoperative and to effect automatic movement of the direction valve into neutral position.

. Still a further object resides in the provision in the hydraulic circuit of a speed control valve, and an hydraulic reset mechanism'operable by dogs on the' translatory element for effecting automatic adjustment of the speed valve.

- A general object of the'invention resides in the provision of a novel pilot reset mechanism which comprises two pressure fluid responsive valves,

each of which has an actuating membermovableinto an operative or an inoperative position, and

which have inter-connecting fluid conduits whereby uponmovement of either member into inoperative position, the other member will automatically be'moved into operative position.

Fi'irther objects and advantages will become apparent as the description proceeds.

In the accompanying drawings,

' appended claims.

Figure 1 is a front view of a machine tool pro- 4 vided with an hydraulic transmission embodying the features of my invention.

Fig. 4 is adiagrammatic representation of the hydraulic system for the carriage, showing the tional working pressure relief valve forming part of the hydraulic system;

I Figure 5. is a viewsimilar to Fig. 4, but show-' ing the parts in the positions occupied to eilect rapid movement of the carriage to the left.

Fig. 6 is a view similar to Fig. 5, but showingthe parts adjusted to effect a slow feed to the left.

Fig. 7 is a view similar to Figs. 5' and 6, but with the parts adjusted to effect a slow feed of the carriage to the right.

Fig. 8 is a fragmentary sectional view taken .Fig. 9 is an enlarged Fig. 10 is a composite horizontal sectional view of the panel taken along broken line Iii-i0 of Fig. 9.

Fig. 12 isa horizontal sectional view taken along broken line |2l2 of Fig. 11. Fig. 18 is an enlarged fragmentary vertical se'ctional view taken along line i'3' |3 of Fig. 11.

. Fig. 14 is a fragmentary view on an enlarged scale of the table control dogs.

Fig. 15 is a fragmentary sectional view taken along line lS-ii of- Fig. 14.

Fig. 16 is a diagram illustrating the table movement. g:

cycle: of

While the invention is susceptibleof various modifications and alternative constructions, I have. shown in the drawings and will herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the inventionto the specific form disclosed, butintend to cover all modifications and alternative constructions falling within the spirit and scope of the inventionas expressed inthe Referring more particularly to the drawings.

the machine in its preferredforin comprises an r elongated hollow base 20. Formed on the top of the base -20 aretwo parallel spaced-longitudinalfragmentary view, par- 7 tially in section, of the hydraulic control panel.

Fig. 11 is a transverse vertical sectional view :taken along line li-'-.il of Fig. 10.

ways 2| (Figs. 1 to a), one of which is serene. the other of which is v-shaped. A table or car--- riage 22 is formed on the undersidewith ways 22 mounted on the ways 2| for horizontal translation or reciprocation. Preferably, the carriage 22 is adapted to support the work to be machined, and hence, is provided with a flat upper mounting surface formed with T-slots 24 for securing the work or work fixtures in position.

Mounted on one end of the base is a tool spindle supporting structure 25 in which one or more spindles 26, extending inwardly over the able metal cutting tool 21, are iournaled. A similar structure .28, rotatably supporting one or more spindles 29 extending inwardly over the other end of the carriage 22 and in respective alinement with the spindles 26 and each provided with a suitable metal .cutting tool 39, preferably is .mounted on the other end of the base 20 so that the carriage 22 upon movement in opposite directions'hetween the structures may bring the work into cooperative relation alternately with i and 29, and adjustable laterally thereof to obtain the desired dimension of revolution.

For each set of opposed spindles 26 and 29, one

or more work pieces may be mounted on the carriage 22., Thus, if two separate work pieces are positioned in proper alinement with the spindles 26 and 29, one piece may be machined upon move; 4

ment of the carria e 22, in one direction ife.

P to the left'into operative relation with the associated spindle 28, and the other piece may be machined upon movement of the carriage in the opposite direction. While one piece is being operated upon, the other finished piece may be replaced by a new piece so that the operation of the machine may be continuous.

The fly tools 21 and 30 may be adjusted to take relatively diflerent depths of cut, and the work may be so mounted that upon movement of the carriage 22 in one directionyone tool willtake a roughing cut; and upon movement of the carriage in the opposite direction, the other tool will work carriage 22 and each provided with a suit- Such machine is especially useful in a,4oo,1aa w A 22 or to the general organization and structuralv details of the machine.

A. novel hydraulic example at a rapid traverse whenever the tools are not talnng a cut, a slow feed during, a roughing cut and a still slower feed during a, finishing cut, and tends to maintain substantially constant any i predetermined feed regardless of any variations.

in the cutting resistance likely to occur inpractice.

In its preferred form, the transmission com,-

prises an hydraulic motor (see Fig. 2) havinga cylinder 9| mounted below the carriage 22 within the base 20. Reciproqably disposed within the cylinder 3| is a piston 32 supported by two piston rods 33 which extend slidabl'y through the. closed opposite ends of the cylinder 3|. Preferably, the

cylinder 9| is rigidly attached to the underside 'of the carriage 22, and the piston rods 93v are secured at their outer ends to the base 20. v The opposite ends of the cylinder 2| are connected through the piston rods 23 respectively to two fluid conduits 34 and 99 leading to a direction valve 36.

The direction valve at (Figs. 11 and 1 2) may" be of any desired construction, and preferably the ends by means of plates 29. A valve piston comprises an elongated cylinder bore or valve chamber 91 formed in a casing 38 and closed at 40 of the spool type is mounted for reciprocation in the bore 31. Formed in'the peripheral wall r of the valve bore 21 are two axially spaced an-,

nular ports 4| and 42 connected respectively to the conduits I4 and 35. Twoinlet ports 43 and 44 located respectively beyond the ports 4| and 42 are also formed in the valve bore 31, and are constantly connected through a pressure fluid supply conduit 45 to a suitable source of pressure fluid, such as a low pressure gear pump 46 (Fig.

4). Formed in. the valve bore 21 intermediate the ports 4| and 42 is an annular exhaust port 41. The valve piston 40 is formed with four longitudinally spaced peripheral collars or heads 1 '48, 49, 50, and 5| defining peripheral spaces 52, 53

take a finishing cut. Either a single work piece or a plurality of alined work pieces may be operated on.

In the present instance, a single engine piston A (see Figs. ,4 to '7), having two diametrically alined wrist pin holes 3 tabs bored, is mounted, as by means of a suitable fixture (not shown), on

the carriage 22 between the tools 2'! and 30.

Movement of the carriage to the left, causes the tool 21 to take a roughing cut in both holes B, and reverse movement of the carriage causes the tool 90 to take a finishing cut in both holes.

The two spindle supporting structures 25 and 29 preferably are allkein construction, and are described in detail in my aforesaid atent. While .one specific form of machine is shown and described, it will beunderstood that the invention vin; its broad aspects is not limited to the specific character or use of the translatory power element and 54. v

It will be evident that upon movement of the valve piston 40 to the left (Figs. .5 and 6), the

space 54 will connect the ports 42 and 44 to sup-- 4 ply pressure fluid to the conduit 35 leading to the left end of the cylinder 3|,and the-space 93 will connect the ports 4| and 41 to establish communication of the conduit 24 from the right end of the cylinder 3| with the exhaust, thus instituting movement of the carriage 22 to the left.

Upon reversing the position of the valve piston- 4ll'(Fig. 7) the spaces 52 and 58 will respectively connect the ports, and and the ports 42 and 41 to reverse the connections, of the conduits 34 and 35 so as to cause the carriage 22 to travel to the right. 1

An automatic reset pilot mechanism responsive to the movements of the carriage 22 is provided for reversingthe direction valve 99. Thepilot mechanism comprises two valves 55 and 56 for effecting reversal of the work carriage 22 respectively to the left and right. The valves and 56 (Figs. 4-to '7) respectively comprise vertical valve bores or chambers 51 and 58 (Fi 9) which may be formed in any suitable casings. and

which in the present instance are formed in a plate or. apron 59 constituting a panel secured to J on is'provided for driving the carriage 22. The transmission is adapted to translate the carriage 22 automati-. cally at any desired variation of speeds, as for valve plun'gers'89 and 8| of the spool type formed respectively with spaced upper and lower peripheralcollars or heads 62 and 88, and 84 and 85 defining annular spaces 88 and 81. The upper end portions of the bores 51 and 58 are adapted to be connected with or disconnected from -a branched conduit 88 by the collars 82 and 84, and the conduit 68 in turn is adapted to be connected through a stop valve 89 either to the source of pressure fluid or the exhaust.

The bores 51 and 58, intermediate the collars 82 and 83, and 84 and 85, regardless of the positions of the plungers 88 and 8|, are always in communication with -the drain through abranched exhaust conduit III. A cross conduit 1| opens at one end to the bottom of the bore 81, and at the other end always to the top of the bore 58 above-the head 84 for connection through movement of the head 84 either with the conduit 88 or the exhaust conduit 10. Likewise, a cross conduit 12 opens at one end to the bottom of the bore 58, and at the other end to the top of the bore 51 above the head- 82 for communication through movement of the head 82 either with the conduit 88 or the exhaust conduit 19. The cross conduits Ii and 12. also open respectively to the left and. right ends of the main direction valve,

'bore 31.

The bores 51 and 88 (Fig. 9) preferably open vertically through the plate 89, and are closed at their lower ends by-plugs i8 and at their upper ends by sleeves ll through which the upper-ends of theplungers 89 and 8| slidably extend. It will be evident that the plungers 80 and. 8| constitute differential pistons which will assume their uppermost positions whenever subjected to pressure fluid at both ends or at their lower ends, and will assume their lowermost positions when subjected to pressure on their upper ends only. The upper outer ends of the plungers 88 and 88. Thereupon, the plunger 80 is-elevated into' operative positions, thereby breaking the pressure connection to the lower end of the bore 58 and the right end of the valve bore 31, and establishing .a connectiontner 'irom 'to the exhaust. As a result, the valve piston 48 is moved to the right to reverse the movement of the carriage 22.

maticaliy or manually to interrupt the translation of the work carriage 22, and in its preferred form comprises a valve bore or chamber 19 opening vertically through the plate59 between thevalves 55 and '58, and closed at the bottom by a plug 80' and at the top by a sleeve 8|. A valve plunger 82 of the spool type is reciprocably disposed in the bore 19, and extends upwardly through the sleeve M to the top of the plate 59. Formed on the plunger 82 are four longitudinally spaced peripheral collars or heads 83, 84, 85 and 88 which define three annular spaces 81, 88 and 89. The plunger 82 thus constitutes a differential piston which when subjected at both ends to the same pressure tends to assume its uppermost position.

The pressure supply conduit is connected through three parallel branch conduits 90, 9| and 92m the bore 19 respectively at the upper and lower ends and at an intermediate point. Interposed in the lower branch conduit 9| is a restricted orifice 93. The exhaust conduit 10' is connected through two parallel branch conduits 94 and 95 to the bore |9 at spaced points inter- .mediate the conduits 98 and 92 and 9| and 92, respectively. A back pressure valve 98 is interposed in the discharge end of the system ahead of the exhaust conduit 19 and beyond the direction valve 38. The pressure conduit 88 for the pilot reset valves 55 and 58 is connected to the bore 19 at a point such that when the plunger 82 is in its uppermost position (Figs. 5 to '7), communication will be established therewith through the space 88 by the main supply conduit 45, and when the plunger is partially depressed (Fig. 4) I or fully depressed, the conduit carriage 22 is dependent on the desired extentfluid (Figs. 5 to 7), and that the right-handplunger 8| is in itsuppermost position (Figs. 5 and 6), pressure fluid from the conduit 88 will then be transmitted through the upper end of the valve bore 81 and the cross conduit I2 to the lower end of the valve bore 88 and right end of the direction valve bore 81; and thelower end of the valve bore U and left end of thedirection valve bore 21 will be connected through the conduit ill, the space 81 and the exhaust conduit 10 to the drain. Hence, the plunger 88 will occupy its lowermost position, and the valve piston 48 will be moved to the left to causethe carriage 22"to travel to the left (Figs. 5-and 6). p I

As the carriage 22 reaches its extreme left position, the dog 18 depresses the plunger 8i (Fig. '7), thereby breaking the exhaust connection from the lower end of the bore 81 and the left end of the valve bore 81, and establishing a connection therefrom to the pressure conduit 88 will be'cut off from the supply conduit and connected to the exhaust conduit 10. Obviously, fully lowering of the plunger 82 will maintain the connection of the conduit 88 through the space 81 with the exhaust conduit 19, and will therefore cause the ends of the main valve bore 8T-to be connected to the exhaust conduit 19 through the valves 85 and 88. f

Pressure responsive means is'provided for automatically centering the valve piston 40 when the occasion arises. This means (Fig. 12) comprises two centering pistons 81 and 98 slidably disposed respectively in two bores 99 and Hill formed in the end plates 59, and adapted to engage-the ends of the piston 40 when urged inwardly. The outer ends of thebores 99 and Hill are connected to a. branched conduit m which opens to the bore 19 at a point such that it willcommunicate through the space 99 and branch conduit with the exhaust conduit 18 when the plunger 82 is elevated (Figs. 5 to 1), and through the space 88 and branch conduit 92 with the supply conduit 48 when the plunger 8: is depressed (Fig. 4). It will be evident that'when the stop valve plunger 92 is depressed to connect both ends oi the main valve bore 21 to the exhaust conduit 18, and simultaneouslyto connect the conduit IN to the supply conduit 40. the impressed pressure fluid in the bores 88 and I will force the centering pistons 91 and 88 into their innermost end ofthe bore, and thecasing I02 and the plate I06 are secured in assembled relation and in position in the'recess I00 by means of bolts I01. The bore I is connected at its inner end to the conduit 88, and is formed at spaced points along'its length with annular ports I08 and I09 connected respectively to the exhaust conduit 10 and a conduit IIO opening into the lower end of the bore 10 beneath the stop plunger 82.

A valve plunger III is 'slidably mounted in the bore I00, and has a stem 2 extending through the .plate I06 and provided with an actuating acookse connect the conduit for a succeeding cycle, the hand valve I02 is actuated manually to connect the conduits 10 and H0, thereby causing the plunger 82 to drop into its lowermost position. released and drops to the left of the plunger 02. The valve I02 is' now actuated manually to eflect return of the plunger 82 to operative position,

-whereupon the work carriage 22 is caused to move to the left and through another cycle.

The work carriage'22 is adapted to be driven automatically at variable speeds, for example at a rapid traverse-when neither of the tools 21 and is in operative contact with the work, and at a slow feed when either tool is in. cutting engagement with the work. Thus, for the blank A, the

knob II3. The plunger III is formed with a peripheral space II4 adapted either to connect or disconnect the conduits 10 and H0. Obviously,

upon actuating the valve I02 to connect the conduits 10 and H0, the lower end of the bore 10 will be opened to the exhaust, and due to the carriage 22 is moved, as'illustrated graphically in Fig. 16, wherein the abscissas represent the extent-of the carriage movement to the left and right of the neutral position and the'ordinhtes indicate the speed of travel to the left and-right, through the following cycle: from the central starting position c to thev left at a rapid traverse along c.'d until the tool 21 is about to contact with the leading hole 13; at aslow feed along ef while the leading hole 3 is being 'rough bored! at a rapid traverse along g-h while the tool 21 is crossing the space between the holes B; at a slow feed along t-d while thetrailing hole B is being rough bored; at-a rap'id traverse along orifice 83 a substantial pressure reduction will ing the latter to descend to stop the work carriage 22. Upon actuating the valve I02, to dis connect the conduits 10 and I I0, the supply presoccur beneath the stop plunger 82, thereby caus- 1 10-1 just before reversal: then upon reversal to the right, at a rapid .traverse along M until the tool 30 is about to contact with the then leading hole B; at a slow feed along o-p while the then leading hole Bis being finish boredrat a sure will again be established on the underside of the sto plunger 82, thus causing the latter to retu'rn upwardly into operative position. Where a roughing cut and a flnishingwut are to be taken upon movement of the work carriage 22 in opposite directions, it is desirable to provide'means for automatically stopping the carriage upon movement thereof after the finishing cut into central or neutral position. This means (Figs. 14 and 15) comprises a pivotaldrop pawl or dog 5- movable with the work carriage 22, and adapted to engage the upper beveled end of the stop plunger 82. The dog .IIB is pivotally mounted by means of a bolt 8 on a plate 1 a before reversal so as to afiord time to stop the secured tothe front of the carriage 22 for adjustment along the T-slot 18. A forwardly pro- -jecting pin II8 on the'plate H1 is adapted for engagement in a slot H8 formed in the right side of the dog III! to limit pivotal movement of v the latter in that direction, The stop plunger 82 and thedog H5 are located forwardly out of range of the reverse plungers 08 and 8|, and preferably for engagement midway of the work carriage 22; v v

It will be evident that the dog II! is movable to the right past the stopplunger 82 without depressing the latter, but upon movement of the carriage 22 to the left into the neutral or loading position, will depress the plunger against the upwardly directed pressure diflerential to stop the carriage. The plunger 82 is not depressed into its lowermost position or sufllciently to. release the dog, although the slight pivotal movement permitted by the pin I I8 causes the pivotal center to be located to the left ,of the plunger. I However, the plunger 02 is depressed suiiiciently and branch conduit 04 to the conduit 10, audio rapid traverse along q-r while the tool 30 is crossing the space between the holesB': at a slow feed along-s-t while the then trailing hole 8 is being finished bored; at a rapid traverse along line 10-21 until reversal; and finally upona reversal to'the left, at a rapid traverse along w-c to the initial starting position. It will be noted that on the final'traverse in each direction, the

tool is caused to move slightly beyond the work tool if desired beforecommencing withdrawal past the center position. Preferably, the intermittent feeds to the right during the finishing cuts are somewhat slower than the corresponding roughing feeds to the left. While'the carri'age movements have been described as applied Y 'to a particular type of work piece, it will be un- -derstood that the programming of the carriage 22 may be varied to suit any desired problem with.- out departing from the spirit and scope ofthe invention,

In the present instance, the impelling fluid pressure 'is maintained substantially constant, as forv example by means of a pressure relief valve H20 interposed in a branch conduit I2I from the main supply conduit 45 to the drain, and the speed control is obtained by automatically. regu-, lating the rate of discharge of pressure fluid from the exhaust end, at any particular time, of the cylinder 3|. The discharge of pressure fluid is.

so regulated thatthe speed of the work carriage 22 is maintained substantially constant during any feeding movement regardless of variations in resistance likely to occur in practice.-

- to connect the conduit 88 through the space 81 The relief valve I20 per se forms no part of the present invention, and may be of any suitable conventional form or type for maintaining a sub- 15 stantially constant maximum workingv pressure IOI tothe branch pressure I conduit. 02, thereby stopping the carriage. To again institute operation'of the carriage 22, as

The dog II! is thereby as is well known in the art. For purposes of iilustration, I have shown in Fig, 4- a conventional type of working pressure relief valve which comprises a housing I20 having an inlet passage I2II compression sprin I20. The spring seats at one.

end against a screw 120 which is adjustable to vary the tension of the spring and thereby working pressure, It will be readily understood that the pressure of the fluid in the. line 45 acts against and tends to urge the valve member I20 from the port I20 against the predetermined pressure of the spring I20, and that fluid will throttie past the valve member to limit the pressure in the line 45.

The specific means for controlling the speed of the carriage movements comprises a speed valve I22 (Figs. 11 and 12) to which the exhaust fluid from the main valve 36 is directed; The

speed valve I22 preferably comprises a bore or bore I23 and constitutes the inlet port for the valve I22. Two annular discharge ports I24 and I25 are also formed in the bore I23 respectively at opposite sides of the port 41.

Reciprocably disposed in the bore I23 is a valve piston I26 of the spool type formed with an annular peripheral space I21 which is adapted.- upon movement of the piston respectively into opposite end positions to connect the inlet port 41 either to the dischargeport I24 or the discharge port I25. The port I24 communicates with a substantially unrestricted discharge passage I28 connected to the exhaust conduit 10, while the port I25 is connected through a passage I29 with means hereinafter described for restricting the flow of fluid. It will be evident that with the piston I26 in its left-hand position, the carriage 22 will be movable at .a rapid traverse, and that with the piston I26 in the opposed position, the carriage will be movable at a slow feed.

A reset pilot mechanism (Figs. 4 to '7) consistv ing of a traverse valve I30 and a slow feed valve I3I is provided for automatically actuating the piston I 26 of the speed valve I22. The valves B0 and I3I preferably are built into an integral structure with the reverse and stop valves 55, 56 and 69, and hence respectively comprise vertical bores or chambers I32 and I33 opening through the plate 59. Of the bores I32 and I33, the lower ends are closed by plugs I34, and the upper ends are closed by sleeves I35. Slidablydisposed in the respective bores I32 and.I33 and extending upwardly through the sleeves I35 are two valve plungers I36 and I31 of the spool type formed respectively with longitudinally spaced peripheral collars or heads I38 and I39, and I40 and I, defining annular spaces I42 and I43. The upper ends of the plungers I36 and I31 above the plate 59 are beveled to constitute, abutments alternately responsive to the movements of the work carriage 22. I The pressure conduit 68 opens to the uppe end portions of the bores I32 'and I33 for connection thereto to supply pressure fiuid when uncovered by lowering of the upper heads I38 and I40. The exhaust conduit .opens to the bores I32 and I33 constantly in communication with the er I36 and I31 A cross conduit I44 opens constantly from the upper end of the bore I32 above the head I38 to the lower end of the bore 133 and to the right end of the speed valve bore I23, and is adapted to be brought into communication either with the pressure conduit 68 or through a branchwith the exhaust conduit 10 upon move- -ment of the plunger I36 respectively into its lowermost or uppermost position. Likewise, a cross conduit I45 opens from the upper end of the. bore I33 above the head I 40 to the lower end of the bore I32 and the left end of the speed valve bore I23, and is adapted to be connected either with the high pressure conduit 68' or through a branch with the exhaust conduit 10 upon movement of the plunger I31 respectively into its lowermost or uppermost position. i

The plungers I36 and I31 by reason of their upwardly projecting ends constitute differential pistons which will seek their uppermost positions when both ends or the lower ends are subjected to the high pressure in the conduit 68, and will take their lowermost positions when subjected to pressure on their upper ends only. It will be evident, that when the traverse plunger I36 is depressed, high pressure will be transmitted to both ends of the bore I 33 and to the right end of the valve bore I23, thus positioning the valve piston I26 (Fig. 5) to effect rapid traverse of the work carriage 22 in a direction depending on the valve 36. The plunger I31 will occupy its uppermost position, thereby connecting the lower end ofthe bore I32 and theleft end of the valve bore I23 to the exhaust conduit 10. 'If the feed plunger I31 is now depressed, the pressure conduit 66 will be connected to the lower end of the bore I32 and the left end of the bore I23. Thereupon, the traverse plunger I36 will be'reset into operative position, and therethrough will connect the lower end of the bore I 33 and the right end of the bore I23 to the exhaust conduit 10 so as to establish the plunger I31 in its lowermost position and effect movement of the piston I26 to the right (Figs. 6 and '7).

A plurality of dogs are mounted on the carriag'e 22 for actuating the piungers I36 and I31. Obviously, the dogs may be varied in number and locationto obtain the desired carriage movements for a given problem. In the present instance, twofixed dogs I46 and I41 are mounted on the front of the table 22, for adjustment along. the T-slot 18, in Position to depress the traverse plunger I36 substantially simultaneously with orbefore each reversal of the carriage movement at the extreme limits of reciprocation. Two drop dogs I48 and I49, pivotally mounted respectively on plates I52 adjustably secured to the front of the carriage 22 along the T-slot 18, are located between the dogs I46 and I41, and are adapted respectively to depress the traverse plunger I36 to institute rapid traverse of the carriage 22 while the tools 21 and 30 successively are crossing the space between the holes B of the work piece A. The dog I48 is limited against pivotal movement to the right past vertical position through engagement of 'a slot I50 therein with a pin I6I over the plunger I36 upon movement with the carriage 22 to the left. 7

Four, additional drop dogs I65, I56, I51 and 6 I88 are pivotally mounted on plates I88 adjustthe casing 88.

ably secured to the front oi the carriage 22 along the T-slot 18 and between the reversing dog 18 and the stop dog H8. The two dogs I88and I88 on the right have pin and slot connections I" with the respective plates I88 preventing pivotal movement to the rightf-past the vertical, and are adapted to successively depress the feed plunger I81 upon movement of the carriage 22 to the left toinstitutethe slow teed while the tool 21 is operating in the work holes 3. The two. dogs I81 and I88 on the left have, pin and slot coniting pivotal movement past the vertical to .the'

- left,'andare adapted to depress the feed plunger I81 up'on"movement of the carriage to the right.

' to efiect a slow teed successively for engagement of the tool 88 with the holes B in the workA,

To provide means for restricting the discharge or exhaust fluid from the valve I22, so as to reduce the speed oi. the. workcarriage 22, the disprises e valve piston in slidably disposed in. the

bore I88. The piston H2 is formed with a peripheral annular space I18 always establishing @nections I8I with the respective plates I88 limcharge passage I28 is adapted to be connected 1 through an orifice or various combinations of orifices to the exhaust passage I28.- To this end, a

plurality of chambers or bores I82, two in the present instance, are formed in the bottom of The chambers I82 are interconnected by a passage I88 which is connected to the exhaust passage I28. The inner ends of the chambers I82 are connected respectively through spaced passages I88 and I88 to a transverse chamber or bore I88 which isiormed in the casing 88- and is connected centrally through the passage I28 to the port I28. Adlustably threaded.

into the chambersv I82 are two heads I81 provided with upstanding pins I88 extending across the passages I82 and I88 to define therewith req stricted orifices I88 and I18.

It-will be evident that fluid discharged from .theport I28'in passing through one or both or the orifices I88'and I18 will be subjected to the flow law or orifices, and will therefore build up I aback pressure checking the speed of the carriage 22 to a predetermined point; The pressure varies as the square or the volume of the fluid flowing throughthe orifices, and hence increased flow'cannot take place unless the rate of travel or the carriage 22 is increased. The velocity of fluid flow past the orifices thus is-proportional to the rate of travel or the carriage 22. The orifices serve to prevent any appreciable fluctuations in the predetermined slow speed of the carriage 22 otherwise tending to result. irom.: variations in dent that the rate oi teed is dependent upon the sizes or the orifices employed, and that difierent rates oi vi'eed may be obtained by selectively varying the number of orifices oi the same or difierent' sizes, connected in parallel at any one time. 'Obviously', thenumber, sizes and combinations oi Preferably, aslower feed is employed durins the finishing cuts than during the roughing cuts.

communication between the passages I28 and I88,

' and adapted whenin its leit-hand'position also to connectthe passage I88 withithe passage I28 so as to obtain a raster feed.

The piston I12 is automatically. moved from *I".

one position to the other upon each reversalfof travel of the carriage 22. The pressure im-- pulses are supplied through the conduits H and 12 which open respectively to the left andright ends of the bore I88. Thus. when the reverse plunger 88 is depressed to institute movement or the carriage 22 to the'leit, pressure fiuidis supplied to the conduit 12 and acts to move the piston I12 to the left, thereby cutting in the orifice I18, to obtain a relatively fast feed during the roughing stroke (Figr 6). Conversely, upon depressing the plunger M to reverse the movement 01' the carriage 22 to the right, the conduit 12 is connected to the exhaustconduit 18, and pressure fluid is supplied to the conduit 1i and acts to move the piston I12 to the right, thereby cutting out the orifice I18 to obtain a slow finishing feed (Fig. '1)

Preferably, the plate or apron 88 constitutes a control panel secured in the, front wall of the 1 base 28. Cover plates I14 and I18 are secured mounted as a unit resistance to the cutting action. .It will be evi- I 1 orifices can be indefinitely multiplied to obtain a wide and flnelygraduated range or feed adjustments. d

to the front and rear-iaces'oi' the panel 88. A

bracket I18 supporting the casing 88 on its underside is secured against the rear or insiderace or plate I18. The passages serving the various valve units are formed mainly in the contacting sur-' faces of the parts 88, I18, I18, I18 and 88. Thus, all oifthe valves are built into an integral hydraulic structure which may be' readily de- 1r in the machine by merely removing the platebg A cover plate I" is secured'to the base ow the plate 88 to enclose the casing 88.

Movement or the carriage actuated reset pilot mechanisms which are ac-' curate, eflicient and reliable'in operation, and

which are simple and compact in construction.

Whenever either 02 the two actuators of each pilot mechanism is operated, the other actuator is automatically reset into position to assume control. By controlling the speed or travel 01' the carriage 22 through the rate or. flow oi the discharge fluid, a smooth and uniform operation is obtained. The orifice control, including the valve I1I, afi'ords means for varying the rate or feed j in" either direction to suit the depth or cut to be taken- The carriage may be operated continuously; or through a predetermined cycle under the control of the dog III. The system is highly flexible and adaptable.

.I claim as my invention:

1. Afluid control system for themovabie element or a machine tool, comprising, 'in combination control means adapted to .be mounted on said element for movement therewith, two pilot valves adapted. to "be mounted-in fixed position in operative i'.elation to said element, each valve comprising a casing and a valve member mo'vable therein and projecting therefrom, each pressure member having an inoperative position and" an operative position {or-engagement by said means,

' casings and controlled by'said members to automaticallyeiiect return Neither-member into operative position upon movement of the other member into inoperative position-by said 'means,- 7

nesto direction and speed is under the control oi. selective dog 1 fluid passages "cross-connecting said controlling the movement 01' said element.

2. In combination with a reciprocable element 1 of a machine tool, control means mounted on said element for movement'therewith, and two spaced separate control devices mounted in fixed -position relative to said element, each device comprising a movable abutment having an operative position in which it is engageable by said control means for movement into an inoperative position, each device controlling the other device to effect movement of one abutment into operative position'upon movement of the other abutment out of operative position by said control means, said control means comprising two sets of a plurality of abutments spaced longitudinally 'ofsaid element for coaction respectively with said devices, said devices and the abutments of both sets being aligned in a single .plane longitudinally of said element, and means operable by one of said devices'for controlling the rate of reciprocation of said element.

3. In an hydraulic system, in combination, a source of fluid under pressure, two valve casings formed respectively with valve cylinders, two valve pistons respectively reciprocable in said cylinders, each of said pistons having a'reduced end projecting from the associated cylinder for outside actuation, and having two longitudinally spaced peripheral heads defining opposed differential pressure areas, a pressure fluid supply passage adapted to connect said source to the smallends of said cylinders when the associated pistons are in their innermost positions, a fluid exhaust passage openin from said cylinders intermediate said heads, and two fluid cross passages respectively opening from the large end of each cylinder to the other cylinder for connection to said supply passage upon movement of the associated piston in said other cylinder into its innermost position or to'said exhaust passage upon movement of the latter outwardly.

4. In a. fluid operating system for a machine tool, in combination, a piston and cylinder unit for reciprocating a movable machine tool element, fluid passages leading respectively to opposite ends of said unit, a source of fluid under pressure, a reversible reciprocatory direction valve having a. closed central position in which it closes said passages and being operable upon movement into opposite extreme positions to connect said source alternately to said fluid passages, fluid pressure responsive means for actuating said valve selectively into either extreme position, independent fluid pressure responsive means for centering said direction valve, a fluid passage leading to said first mentioned pressure responsive means, a fluid passage leading to said last mentioned pressure responsive means, and a stop valve automatically operable upon movement of said element into a, predetermined position to disconnect said second last mentioned passage from said'sourceand to connect said source to said last mentioned fluid passage.

5. In a fluid operating system for a machine tool, in combination, a source of fluid under pressponsive means for actuating said valve selecfirst mentioned pressure responsive means, a fluid being operable upon movement in opposite directivelyjnto either extreme position, independent fluid pressure responsive means-tor centering said direction valve, a fluid passage leading to said passage leading to said last mentioned pressure responsive means, an exhaust passage, and a stop valve movable in opposite directions to connect said last two mentioned fluid passages respectively and interchangeably'to said source and exhaust passage.

' 6. In a machine tool, in combination, a mov-, able machine element, a piston and cylinder unit for reciprocating said element, fluid passages leadingrespectively to opposite ends ofsaid unit,

.a source of fluid under pressure, a reversible direction valve having a closed central position and tions to connect said source alternately to said fluid passages, pressure responsive means for centering said direction valve, a, fluid supply passage leading to said responsive means, a stop valve comprising a cylinderand a differential valve plunger in said cylinder, said source being connected through three branch passages respectively to said cylinder at opposite sides of said ,plunger and at an intermediate valve port, the

reduced end of said plunger extending out of said cylinder for automatic actuation inwardly by cylinder at the large end of said plunger to said exhaust passage, said plunger upon movement inwardly serving to connect said port to said fluid supply passage, and when in its outermost position serving to connect said fluid supply passage to said exhaust passage. V 7. In a machine tool, in combination, a movable machine element, a piston and cylinder unit for reciprocating said element, fluid passages leading respectively to opposite ends of said unit, a source of fluid under pressure, a reversible direction valve movable in opposite directions to connect said source selectively to said fluid passages to effect movement of said element alternately in opposite directions, andmovable into an inoperative position to stop said element, pilot valve means for reversing saiddirection valve, a

, fluid supply passage leading to said means, a stop valve comprising a casing and a plunger in said casing, said source being connected to said casing through a valve port, one end of said plunger extending out of said casing forautomatlc actuation inwardly by said machine element upon movement of the latter into a predetermined position, an exhaust passage, said plunger upon movement inwardly serving to connect said supply passage to said exhaust passage,.and when in its outermostposition serving to connect said supply passage to said port, means operable upon inward movement oi said plunger to effect movement of said direction valve into said inoperative position, and means for actuating said stop valve to return said plunger into extended position.

8. In a fluid operating system for a machine tool, in combination, a reversible direction valve having an inlet passage adapted for connection valve being movable in opposite directions to connect said inlet passage alternately to said mus passages, and the discharging passage: of said fluid-.es to said exhaust passage; a speedvalve in said exhaust'passage controlling the rate of fluid discharge from said unit, a pilot valve means adapted to be responsive to the movement of said element for reversing said direction valve, a pilot valve means adapted to be responsive to the movement oi. said element for adjusting said "speed valveon occasion, a fluid supply passage leading to both pilot valve means, and a valve adapted for connecting said supply passage to said source.

9. Ina machine tool, in combination, a source oifluld under pressure,,a fluid passage, anex 'haust passage, a-valve comprising a casing and a diilerentialplunger in said casing, said source being connected through .three branch passages respectively to said casing at opposite sides of said plunger and at an intermediate valve port, the reduced end of said plungerextending out oi said casing for outside actuation, said plunger when in its-outermost position connecting said fluid matically operable upon each reversal of said elepassage 'tosaid port, a restrictedoriflce in the bran'ch passage opening to the'inner end of said casing, a hand-valve comprising a casing and a valve plunger reciprocable therein, and a bleed passage connecting the inner end 01' said valve casing to said hand valve casing, said fluid passage opening to one end oi! said hand valve casing,

ment to vary the number or said orifices connected in said exhaust passage.

13. In a machine tool, in combination, a source 01' fluid iimder pressure, a supply passage opening from said source, a fluid passage, a valve having a pressure responsive-plunger, means including a restricted oriflce for directing pressure fluid from said supply passage to one end of said valve to urge said plunger into an operative position in which it connects said supply passage to said fluid passage, an'exhaust passage, a hand. valve having a pressm'e responsive valve member, said fluid passage being connectedto direct pressure fluid to said hand valve against one end of said valve member to urge the latter out oi! an operative position in which itis adapted to connect said end oi! said first mentioned valve to saidexhaust passage, and means for moving said valve member I a into operative position.

14. Ina machine tool, in combination, a casing,

. a differential plunger reciprocable in said casing,

said last'mentioned plunger upon movement toward said end of said hand valve casing connecting said bleed passage to said exhaust passage.

10. In a machine tool,,in combination, a movable machine element, a-piston and cylinder unit for reciprocating said element, a source of fluid under asubstantially constant pressure, a supply passage leading vfrom said source, fluid passages leading to opposite endsoi said unit, an exhaust passage, a direction, valve for connecting said fluid passages respectively and reversibly" to said supply and exhaust passages, pilot valve means responsive-upon movement of said element into either end position to reverse said direction valve,

A two discharge passages, a speed-control valve for connecting said exhaust. passage alternately to said discharge passages, pilotvalve means re sponsive upon movement of said element into various predetermii'zled positions to reverse said speed-control valve, two parallel restricted orifices adapted to be connected in one or said discharge passages, and a feed valve responsive to,

said first mentioned pilot means for selectively connecting one or both 01' sald'orlflces'in said last mentioned discharge passage. 1l.-In a machine tool, in combination, a movable machine element, a piston and cylinder unit for reciprocating said element,' a source of fluid under a substantially. constant pressure, a supply passage leading from said source, fluidpassages leading to opposite ends ,of'said unit, an exhaust passage, a direction valve for connecting said fluidpassages respectively and reversibly to said supply and'exhaust passages, a plurality oi-di'scharse passages, a speed-control valve forconnectmgsaid exhaust passage selectively to any one of I said discharge passages, a plurality of parallel restricted orifices adaptedto'beconnected in one said last mentioned discharge e.

l2. In a machine tool, in combination, a movable machine element, a piston and cylinder unit of said discharge passages. and a feed valve for connecting said orifices in various combinations in 7d I for reciprocating said element, a source of fluid I under a substantially constant ressure, a supply a source of fluid under pressure, a supply passage opening from said source and termlnatingln a discharge port opening to said casing, a fluid passage having an inlet port opening from saidcasing, means for directing pressure'fluid from I said supply passage to said casing at opposite sides '01 said plungerto urge said plunger into an op-' 'erative position in which it establishes communication to connectsaid supply passage and said; fluid passage, means operable at will for dissipat-- 'ing the pressure fluid in said casing acting on the larg'e side of said plunger-to eflect movement of: ,said plunger out of operative position and thereby interrupt said communication, and means opera tively connected to said fluid passage for actuation by fluid under pressure.

15.111 a machine tool, in combination, we

valves, each valve having a casing with a closed end-and a diflerenti'al valve plunger reciprocable therein and projecting from the other end theme or, a fluid pressure supply passage opening to said casings, an exhaust passage opening to said casings, and. two passages-cross-connectlng said casings, each cross passage opening atone end to the closed end 01 one atthe other end to the other-casingior connection to said supply passage or said exhaust passage respective-' ly upon movement or theassociated plunger .in-

wardly or outwardly;

- 16. In a machine toolpin combination, two I valves, each valve having a casing with,.a .clo sed end and a valve plunger reciprocable therelnand" projecting from the other end thereof, a fluid pressure supply passage opening-tosaid. casings, and two passages cross-connecting said casings; 'each cross passage opening atone end to' the.

closedend 01' one casing and at the other end 'to the other casing for connection to said supply passage upongnovement oi the associated plunger inwardly.

- l7.-Iri' a machine tool, combinationg two valves, each valve having a casing with a closed" end and adifferential valve plunger reciprocable therein and projecting i'rom the other end thereof, a'fluid pressure supply passage.openmg to said casings. an exhaust re t t op in to said casings, two passages cross-connecting said casings, each cross passage opening at one end to the closed end of one casing and at the other end to the other casing for connection to said supply passage or said exhaust passage respectively upon movement of the associated plunger inward or outwardly, a movable member, a piston and cylinder unit operatively con-' nected'to said member, fluid passages connected to opposite ends of said unit, means including a reversible direction valve for controlling, the supply and exhaust of pressure fluid selectively to and from said fluid passages, to effect movement of said member alternately in opposite directions, said cross passages being connected respectively to opposite'ends of said direction valve, and means on said member for alternately moving said plungers inwardly.

18. In a machine tool, in' combination, two valves, each valve having a casing with a closed end and a differential valve plunger reciprocable therein and projecting from the other end nected in one of said discharge passages, and means for connecting said orifices selectively into said last mentioned discharge passage, said means being automatically operable upon each reversal of said element to vary the selection of said orifices.

22. In combination with a movable element of a machine tool and a piston "and cylinder unit for reciprocating said element, fluid passages adapted to lead respectively to opposite ends of said unit, an "exhaust passage, a source orfluid under pressure, reversible direction val've' neans for connecting said fluid passages alternately to said source and to said exhaust passage; means adapted to be mounted for movement with said element for actuating said valve means, and second valve means adapted to be responsive to the movement of said element into predetermined position for controlling the rate of flow through said exhaust passage, said twomentioned valve means being formed in a'unitary sectional housing, passages to and from said valve means in thereof, a. fluid pressure supply passage opening to said casings, an exhaust passage opening to said casings, two passages cross-connecting said casings, ea'ch cross passage opening at one end to the closed end of one casing and at the other'end to the other casing for connection to said supply passage or said, exhaust passage respectively upon movement oi! the associated L Dlunger'inwardly or outwardly,and a reversible pressure fluid responsive member, said cross passages being connected respectively to opposite ends of said member.

a 19. In a machine tool, in combination, a movable machine element, a piston and cylinder unit passage.

20. In a machine tool, in combination, amovable machine element, a piston and cylinder unit said housing being formed .by complementary grooves in the contacting faces of the sections oi said housing.

23. in an hydraulic system, in combination, a source of fluid under pressure, two hydraulic valves .connected to said source, two hydraulic motors for actuating saidvalves respectively, each valve having an operative posltion 1n wmcn it is adapted Ior outside actuation, and an opposed position, and controlling the operation of the motor ror the-other valve, whereby actuation of either valve from the operative position into the opposed position will eiIect movement of the other valve from the opposed position into the operative position, and means reversibly operable in response to t e adjustment of said valves.

24. In a machine tool, in combination, a reciprocaple machine element, a piston and cylinder unit for reciprocating said element, fluid passages leading respectively to opposite ends of said unit, a source oi. fluid under pressure, a reversibl direction valve operable upon movement into opthe connection of said orifices in said exhaust for reciprocating said element, a source of fluid under a substantially constant pressures. supply passage leading from said source, fluid passages leading to opposite ends of said unit, an

said fluid passages respectively and reversibly to said supply and exhaust passages, a plurality oi restricted independently adjustable orifices adapted to be connected in said exhaust passage, and means for connecting said orifices selectively into said exhaust passage I 21. In a machine tool, in combination, a mov- .56 exhaust passage, a direction valvefor connecting able machine element, a piston and cylinder unit for reciprocating said element, a source of fluid under a substantially constant pressure, a supply passage leading from said source, fluid pas sages leading to opposite ends of said unit, an

exhaust passage, 2. direction valve' for connect posed end positions toconnect said source selectively to said passages to effect movement of said element in opposite directions and having an intermediate neutral position for stopp n said element, said valve comprising a casing and a reciprocatory valve member, means for actuating said member, two adjustable abutments having a projected position in which they act to confine said member in said neutral position and having a retracted position in which said member is free ior'actuation by 'said means, an exhaust passage, hydraulic means for moving said abutments simultaneously into projected position, and means for connecting said hydraulic means either to said I source or said exhaust passage.

25; In combination with a hydraulic actuator for propelling machine parts and the like which includes a cylinder and piston construction, pumping means for delivering fluid under pressure for propelling purposes to said actuator, a main fluid control valve operatively connected therewith and including a reciprocable valve member ior'controlling the delivery of said fluid to said actuator, and a fluid control means including a restricted orifice, a less restricted oriflee, and a valve having a reciprocable valve member for operatively connecting said restricted oriflce to receive fluid discharged from said actuator when said actuator moves at a feeding rate and for operatively connecting said less restricted oriwhen said actuator moves at a faster rate.

26. In a machine tool, in combination, a movable machine element, a piston and cylinder unit 7 for reciprocating said element, a source of propelling fluid under pressure, and a fluid conducting system operatively connecting said source and said unit, said system including a direction valve having a chamber and a valve member reciprocably adjustable in saidchamber and adapted to direct fluid from said source to one end of said unit and to direct fluid discharging from the other end or said unit during the traveloi said element in one direction, a restricted passage and a relatively unrestricted passage in parallel and adapted selectively to receive the fluid discharging from said unit during said travel, and selective valve means for said passages, said valve means having a chamber and a valve member reciprocably adjustable in said last mentioned chamber and efiective in one position 01 adjustment tocause the discharge of fluid through said restricted passage andin another position or adjustment to permit the discharge or fluid through said unrestricted passage.

27. In a machine tool, in combination, a 'reciprocable machine tool element, a, piston and cylinder unit for reciprocating said element, pumping means for delivering liquid fluid under pressure, and a fluid conducting system operatively connecting said pumping means and said unit, said system including a direction valve having a valve member reciprocably adjustable and adapted in one position of adjustment to direct fluid from said pumping means to one end of said unit and to direct fluid discharging from the other flce to receive fluid discharged from said actuator fluid, a relatively restricted exhaust passage, a relatively less restricted exhaust passage, and

control means operable to connect said discharge passage selectively to either or said supply passages and to direct'fluid discharging from the other of said supply passages during operation oi said motor in either direction selectively through only said restricted exhaust passage or through said less restricted passage, said relief valve being open when the exhaust fluid is directed through only said restricted passage to cause said element to travel at a relatively slow rate.

29. In a hydraulic transmission for a reversible machine tool element, in combination, a constant displacement pump for providing a source oi fluid under pressure 'and'having a discharge passage,

' a spring-closed adjustable working-pressure relief valve connected to said discharge passage and adapted to open in response to a predeter mined pressure in said passage and to divert excess fluid from said passage to maintain said pressure substantially constant, a reversible hydraulic motor for driving said element and, having su ply passages openingto opposite sides respectively and reversibly to'receive and exhaustfluid, a relatively restricted-exhaust passage, a

relatively less restricted exhaust passage, and control means automatically operable in response to end of said unit during the travel of said element in one direction, and in another position :0! adjustment to direct fluid from said pumping means to the other end of said unit and to direct fluid discharging from said one end of said unit during the travel orsaid element in a reverse direction, means automatically operable upon travel .movement of said element into diflerent prede termined positions to connect said discharge pa sage reversibly to either of said supply passages and to direct fluid discharging from the other of said supply passages during operation of said motor in either directionselectively through only said restricted exhaust passageor through said I less restricted passage, said relief valve being open when said fluid is directed through only said restricted passage to cause said element to travel at a slow rate. v a i I 30. In a hydraulic transmission for a reversible 'machine tool element, in combination,- a source of fluid under pressure having a discharge passage and being responsive to the pressure in said of said element in said reverse direction into a V predetermined position to adJust said valve memher from said other position into said one position, a restricted passage and a relatively unrestricted passage inparallel and adapted selectively to receive the fluid discharging from said unit during travel of said element'in said one direction, selective valve means tor said passages and having a valve member reciprocably adjustable and effective in one position of adjustment to cause the discharge vof fluid through said restricted passage and in another position or adjustment to permit thedischarge. or fluid through said unrestricted passage, and means including an actuating dog movable with and selectively adjustable in relation to said element and bein automatically operable to adjust said last mentioned valvemember upon movement 01 said ele-,

ment into a predetermined position of travel.

28. In a'hydraulic tron for a reversible machine tool element, in combination, a constant passage to vary the volume of fluid available as required to maintain said pressure substantially constant, a reversible hydraulic motor for driving said-element and having supply passages opening to opposite sides respectively and reversibly to receive and exhaust fluid, a relatively restricted I exhaust passage, a relatively less restricted exhaust passage, and; control means operable to connect said discharge line selectively to either of said supply lines and to direct the fluid discharging'fr'om the other of saidpassages upon operation of said motor in either'direction selectively through only said restricted passage or through said less restricted passage, whereby the selection of said exhaust passages permits of a predetermined program of fast and slow. movements of said element in either directional operation.

31. In a fluid operating system for amachine tool, in combination, a direction valve having fluid passages adapted for connection to opposite ends of a piston and cylinder unit for reciprocating a movable machine tool element and having an inlet passage for receiving fluid under a substantially constant pressure and having an ex- 'haust passage, said valve being operable to connect saidfluld passages respectively and interchangeably to said supply and exhaust passages. a plurality of restricted independently j table orifices adapted to be connected in said exhaust passage, and means ior connecting said orifices selectively into said exhaust passage. 

